The invention relates to an attachment device for a vehicle steering wheel in the case of which a connection adapted to prevent relative rotation between the steering wheel and the steering shaft is produced by means of interlocking splines.
In addition to the connection preventing relative rotation between the steering shaft and the steering wheel, means is required for axial location or locking of these vehicle components. The axial locking action, which is in accordance with the state of the art, is achieved using a nut, which is screwed on the free end of the is steering shaft. This type of attachment of the steering wheel is intended to meet the need during final assembly operations on the vehicle and after conclusion of the setting of the geometry of the steering system to be able to readily remove the steering wheel from the steering shaft for the compensation of all cumulative tolerances and to slip the same onto the shaft in the correct angular setting, since the nut may be released and then tightened again with only a few movements of the hand. A correction of the angular setting of the steering wheel is furthermore necessary after resetting of the steering system geometry. Since the conventional steering wheel attachment means has come to be accepted as regards reliability, simplicity and the convenient possibility of dismounting the steering wheel, such system is adhered to, although in some aspects it has disadvantages.
Vehicles are, on an ever increasing scale, being fitted with gas bag occupant restraining systems. On the driver's side, the air bag is customarily integrated in the steering wheel with a pyrotechnic gas generator. During fitting of the steering wheel, the so-called air bag module may only be installed after completion of the attachment on the steering shaft. Although systems with an annular gas generator and a toroidal gas bag have been proposed (see U.S. Pat. No. 4,828,286), the toroidal configuration of the gas bag limits the freedom of design when optimizing the system.